Castle Geyser, shown while in its noisy steam phase, is located in the Upper Geyser Basin of Yellowstone National Park near the Old Faithful Inn. The Castle Geyser eruptions occur every 10-12 hours and typically last for 15 to 20 minutes. During the eruption phase the hot water can reach a height of 90 feet which is then followed by a noisy steam phase lasting 30-40 minutes. The geyser was given the name "Castle Geyser" by Lieutenant G.C. Doane in 1870 because of its fortress like appearance. The 12 foot sinter was carbon-14 dated to around 1022 which is much younger than the previously presumed age of 5,000 to 15,000 years. Photographed 08/06